The immune system is the body’s first line of defense against infection. Given the current outbreak, it is especially important to strengthen the immune system — a feat one can kickstart by increasing his vitamin C intake.

Vitamin C, a water-soluble micronutrient, is known for its immune-boosting properties. It is also a powerful antioxidant that can reduce inflammation, combat disease-causing free radicals and stimulate the production of white blood cells that ward off pathogens.

Guava leaves are commonly used as an herbal medicine to treat colds and digestive problems. But the fruit itself is an excellent source of vitamin C. Just one cup of guava contains 377 milligrams (mg) of vitamin C, making it a potent immune-boosting food. It can be eaten raw as a quick snack or juiced to treat coughs and sore throat.

Red sweet pepper

Red sweet pepper is simply a green bell pepper that has matured into a mellow and sweet-tasting vegetable. A large sweet pepper contains a whopping 209 mg of vitamin C, which is even higher than the vitamin C content of oranges. It is a highly versatile food as well. Snack on sweet pepper strips or roast whole bell peppers to eat alongside casseroles.

Kiwifruit

With 74.7 mg of vitamin C and plenty of antioxidants, the tangy kiwifruit is extremely nutritious. Its immune-boosting properties protect cells and DNA from damage caused by pathogens. Additionally, it has micronutrients like vitamin E, folate and potassium that contribute to overall health and well-being.

Orange

Oranges are one of the most popular vitamin-C-rich foods worldwide. This citrus fruit contains an incredible 82.7 mg of vitamin C, as well as 120 grams (g) of water that keeps the body hydrated. Orange also has high concentrations of beta carotene, the red-orange pigment that colors many bright fruits and vegetables. Upon consumption, the body converts beta carotene into vitamin A, an anti-inflammatory agent that complements vitamin C’s immune-boosting properties.

Grapefruit

Although the bittersweet grapefruit is not everyone’s cup of tea, it packs a modest 38.4 mg of vitamin C that strengthens immune responses to disease-causing pathogens. It is also a good source of dietary fiber, which increases nutrient absorption in the gut. Like oranges, the grapefruit is typically eaten as a quick and juicy snack. (Related: Grapefruit juice protects against weight gain and diabetes.)

Brussel sprouts

With 72 mg of vitamin C, a cup of Brussels sprouts can improve immune functions and reduce inflammation. Like most cruciferous vegetables, Brussels sprouts are also an excellent source of phytochemicals and antioxidants that increase the immune-boosting effects of vitamin C. In particular, plant compounds known as flavonoids and carotenoids prevent cellular damage caused by bacteria and viruses. Toss a couple of sprouts into a bowl of leafy greens or roast the sprouts alongside garlic cloves.

Broccoli

Broccoli has an impressive nutrition profile due to its high concentrations, not just of vitamin C, and dietary fiber, but also, heart-healthy potassium. In fact, just three ounces of broccoli contains 78 mg of vitamin C and trace amounts of immune-boosting vitamin E, iron and zinc. Moreover, broccoli has a good amount of high-quality protein, an essential macronutrient that strengthens immune cells and antibodies. To enjoy the benefits of broccoli to the fullest, it’s best to eat it raw or steamed.

A strong immune system can significantly reduce the risk of contracting the new coronavirus disease. Eat plenty of vitamin-C-rich foods to enhance immune functions and improve overall health.